In North America alone, there are more than 224,000 public and private at-grade railroad crossings. Of these railroad crossings, 137,699 or 61% are located on public roads. Of the railroad crossings on public roads, 51% comprise passive railroad crossings and 49% comprise active railroad crossings. Passive railroad crossings are non-electrified and denoted by fixed signage (e.g., crossbucks, stops signs, yield signs) or nothing at all. Active railroad crossings are electrified and include fixed signage in addition to warning systems with flashing lights and gates to more effectively warn vehicles of the presence of trains on approach.
The United States Department of Transportation (USDOT) has studied safety effectiveness of railroad crossing warning systems and found that upgrading a passive railroad crossing to an active railroad crossing with a flasher warning system increased warning system effectiveness by 70% while upgrading a passive railroad crossing to an active railroad crossing with gates and flashing lights increased warning system effectiveness by 83%. However, the majority of passive railroad crossings in the United States remain so out of economic necessity. Passive railroad crossings are expensive to convert to active railroad crossings. A passive railroad crossing can be converted to an active railroad crossing by adding more than $150,000 of equipment, adding track circuits to detect trains on approach, and establishing commercial power at the crossing site.
Between 2002 and 2012, there were 28,125 accidents at railroad crossings in the United States resulting in 14,176 injuries and/or fatalities. Various causes were cited by the Federal Railroad Administration (FRA) statistics on reported and investigated accidents for this ten-year period, but most accidents were related to driver inattentiveness. According to the FRA statistics, 0.9% of accidents were caused by driver impairment, 40.0% of accidents were caused by driver inattentiveness, 11.3% of accidents were caused by driver misjudgment, 23.1% of accidents were caused by driver violation, 0.5% of accidents were caused by driver unawareness or environmental factors, 0.7% of accidents were caused by a driver being unable to stop (e.g., weather related), 0.1% of accidents were caused by crossing signal malfunction, 10.9% of accidents were caused by deliberate disregard for a crossing signal, and 12.5% of accidents were a result of other causes.
Causes for driver inattentiveness can include distractions associated with cellular telephone or in-vehicle entertainment system use and other activities that take a driver's attention away from the road long enough for the driver to miss a sign at a railroad crossing or an active signal that warns of an approaching train. In addition, some drivers frequently travel the same route and can become desensitized to the presence of a railroad crossing, especially a passive railroad crossing located in a rural or lightly traveled road only equipped with crossbuck signs.
Over the past fifteen years there have been a variety of approaches introduced and tested to address safety at railroad crossings. One approach utilizes a transceiver on a train that communicates directly to radio receivers mounted in vehicles or indirectly through trackside transceivers. In another approach, a K-band radar signal is sent from a trackside transceiver to a specially modified radar detector in a vehicle. In another approach, a vehicle-borne receiver attempts to recognize a train horn acoustic signature to trigger a driver alert.
However, previous approaches have not been successful. Previous approaches have failed for a number of reasons including (1) cost, complexity, and railroad risk of train mounted transceivers, (2) cost and complexity of integrating a receiver into a vehicle either as an aftermarket dash-mounted device or as an original equipment manufacturer (OEM) in-dash feature, (3) unsatisfactory false triggering and missed event performance, and (4) inadequacy for use at non-electrified passive crossings.